The present invention relates to magnetic tape cassettes, and more particularly to a novel audio compact cassette which is equal to or smaller than a "Phillips" type compact cassette.
Recently, cassette tape recorders have been reduced both in size and in weight, and accordingly magnetic tape cassettes have also been miniaturized. Therefore, there has been a strong demand for the provision of small magnetic tape cassettes which are suitable for high quality high density long play recording and reproducing operations. Magnetic tape cassettes satisfying this requirement are operated according to a digital system such as a PCM (pulse code modulation) system in which recording and reproducing operations are carried out with the input signals being converted into pulse signals. In this system, the recording frequency band must be about five times as wide as that of a conventional audio tape. Therefore, video tape cassettes of a size larger than compact audio cassettes are extensively employed with this recording system.
Video tape cassettes are typically operated in a so-called rotary head system. The video tape cassettes have a guard panel which is upwardly swingable and which closes the opening formed in the front part of the cassette. The guard panel prevents the entrance of dust and protects the magnetic tape from damage.
The invention relates to a very small magnetic tape cassette which, as in video tape cassettes, employs a relatively wide frequency band recording and reproducing system. The cassette is usable with audio devices, and is equal to or smaller in size than the conventional compact audio cassette. It is envisioned that the present magnetic tape cassette may be frequently used outdoors and in other less than ideal circumstances. In addition, it is expected that the tape cassette will be carried without its storage case, similarly to audio tape cassettes. Accordingly, the invention provides a construction which is impact resistant, highly dust proof, and less susceptable to jamming than conventional cassettes.
Similar digital audio type magnetic tape cassettes have been proposed in the art. For example, co-pending application Ser. No. 783,397, filed Sept. 9, 1985 now U.S. Pat. No. 4,719,529 (59-153111) discloses a magnetic tape cassette having a guard panel which is swingable upwardly as in the typical video tape cassette, and a slide guard which is slidable back and forth on the bottom of the cassette. The slide guard is urged forwardly in order to close the lower part of the opening formed in the front part of the cassette. That is, it is urged to close a part of the opening through which the tape withdrawing member of the magnetic tape recording and reproducing device is inserted into the cassette.
The slide guard is engaged by suitable members within the reproducing device and is slid towards the rear end of the cassette to open this opening when the cassette is used. Therefore, it is necessary that the slide guard be shaped and designed so as to be easily slidable on the cassette body. Furthermore, in order to miniaturize the cassette body, it is essential for the slide guard to be made of a thin plate material or the like.
The slide guard may be formed by molding plastic material or by using a thin metal material. However, the slide guard thus formed has deficiencies in that the slide guard may readily be removed from the cassette body by plastic deformation over time, or deformation due to molding strain or external mechanical pressure. Of course, a shock imparted to the cassette body when the same is dropped, for example, can cause the slide guard to come off of the cassette.